The present invention relates to a mooring system for floating bodies such as buoys, drilling rigs, cargo ships or the like. More specifically, the mooring system of the present invention employs an improved hinge link to connect the lengths of cable where the hinge link is capable of flexing about an axis, such as where the cables are taken up on a drum or winch, without damaging or abrading adjacent cable sections.
In the field of mooring floating bodies, such as buoys, drilling rigs, ships, or the like, it is the practice to use specifically designed vessels for handling the mooring apparatus. Such vessels are conventionally equipped with a take-up winch or drum amidships and a stern roller such as the arrangement disclosed in U.S. Pat. No. 3,889,621. In the installation or disassembly of a mooring system, cable is either fed out or taken up by the main winch, located amidships, with the cable passing over the stern roller in the mooring operation. Typically, as water depths vary, so must the number of joined cable sections vary in a mooring system. Thus, efforts in this field have been directed toward developing a hinge link which is employed to join cable sections securely together.
A number of hinge link structures are known where the link is capable of assembly to join chain links and flexing or pivoting of the link sections about a hinge axis. For example, see U.S. Pat. Nos. 2,369,344, 2,777,284, 2,972,223, 3,828,550, 3,899,873, and 3,994,127.
The use of lengths of chain in a mooring system has proved to be cumbersome and time-consuming in view of the great weight of such chains and the space which they occupy when stored. Accordingly, wire cable sections have come to be used in the place of chains in many mooring applications. However, in establishing connections or hook-ups between sections of wire cable, it has been the practice to employ U-shaped shackles which are closed by means of a threaded bolt in establishing the hook-up. For example, manufacturers provide the cable sections, at their ends, with hawser thimbles or spelter sockets to facilitate the interconnection between cable sections. The U-shaped shackles would be employed either with or without the hinge links of the prior art to effect such hook-ups since the U-shaped shackles could be easily disassembled when it was desired to remove or add sections of cable to the mooring line.
The hinge links of the prior art, in general, have been employed to establish connections between sections of chain which connections were intended to be of a permanent nature. Thus, the hinge links of the prior art were intended to function as substitutes for a damaged link in a chain and thus are difficult, if not impossible, to open once installed without damaging or destroying the hinge link itself. In other forms of hinge links for lengths of chain, where the link could be disassembled, the assembled hinge link structure was characterized by having sharp protruberances much like the bolt connection of the U-shaped shackles so that, where such hinge links and/or U-shaped shackles were used with wire cable, the wire cable would become abraded and the strands cut by the hinge links or shackle bolts when the cable rubbed against these elements.
Still other types of chain links have been proposed but such are not useful with cable-type mooring systems since they either do not provide the ability in the link of hinging about an axis or are disassembled by virtue of such hinging such as in U.S. Pat. No. 418,812 and thus do not provide secure connections.
The present invention overcomes the foregoing difficulties by providing a mooring system wherein sections of cable can be quickly and easily joined together, as desired, in the system without danger of the connections damaging the structure of the wire cables either during the laying or taking up of the mooring system or storage of the cable on a drum. The invention includes an improved hinge link structure used in the combination and which is distinguished by the ease with which the hinge link can be assembled and disassembled in making and breaking connections between cables. In addition, the hinge link of this invention will be substantially less expensive to manufacture than those heretofore available but which will provide a durable and reliable link under a broad range of operating conditions and environments.
The mooring system of the present invention includes sections of wire cable with each section of cable having an attachment loop in the form of either a hawser thimble or a spelter socket securely attached to each end of each cable section. The spelter sockets or hawser thimbles of adjacent wire cables are joined together by the improved hinge link of the present invention so that no sharp edges or protruberances exist at the connections which can damage the structure of the wire cable during either the laying or taking up of the cables. The hinge link comprises two identically shaped, smooth surfaced half-link sections each of which are U-shaped and provided at the free ends of each of the legs of the U-shaped sections with pin-receiving portions having aligned transverse bores. On the outside surface of each of the legs, a recess is provided having means for receiving the head of a retaining pin so that the head will be flush with the surface of the leg. The retaining pin is provided with a bore spaced along the axis thereof a selected distance from the head, the bore being adapted to receive a cotter pin which, when inserted in the bore of the retaining pin, will abut the interior surface of a pin-receiving portion of a half-link to restrain the pin from axial movement in the transverse bores of the pin-receiving portions of the half-link. Means are also provided for facilitating grasping and rotating of the retaining pin to simplify the steps of removing same when it is desired to assemble and disassemble the hinge link.
With this arrangement a secure connection can be quickly established between wire cable sections and yet can be very easily undone while the hinge link is characterized by its smooth surface which eliminates the possibility of damage to the wire cable.
The foregoing and other features will make the hinge link of this invention particularly useful in a mooring system for a drilling rig, vessel or buoy since, as previously noted, as water depths vary, so must the number of joined cable sections vary in a mooring system. The ease with which cable sections can be added or removed from the system is, of course, primarily dependent on the type of hinge link member employed.